This application claims the priority of German Application No. 100 48 250.3, filed Sep. 29, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a control device for controlling an internal combustion engine with a variably controlled valve stroke and a butterfly valve in an intake tract of the engine.
Such a control device is known for example from German patent document DE 198 47 851 A1 (having U.S. counterpart U.S. Pat. No. 6,039,026, the specification of which is incorporated by reference herein). The known control device triggers an increase in the opening of a throttle (butterfly) valve in the intake port of an internal combustion engine with a variably controlled valve stroke at a low or medium-type load of the internal combustion engine in order to reduce a so-called undesirable xe2x80x9cpumping lossxe2x80x9d.
Internal combustion engines with variably controlled valve strokes, however, exhibit large variations between the desired valve stroke target and the actually adjusted valve stroke in the unrestricted state. These standard deviations are dependent upon tolerances and can have a positive or negative effect. This uneven distribution leads to an uneven combustion air ratio during operation of the internal combustion engine, which in turn leads to increased uneven running.
The goal of the invention is to improve a control device of the above-described type in such a manner that the method for controlling the internal combustion engine, which is executed by the control device, increases the comfort level, reduces fuel consumption and prevents unnecessary efficiency deterioration.
This goal is achieved by a control device for controlling an internal combustion engine with a variably controlled valve stroke and with a butterfly valve in an intake tract. The control device is equipped with means to monitor the smooth running of the internal combustion engine. The control device is also equipped with means through which the butterfly valve is actuated in the closing direction when a defined uneven running threshold value has been exceeded and when the valve stroke is smaller than a specified threshold, until the value drops below the uneven running threshold value again.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.